1. Field of the Invention
The present invention relates to a channel adapter configured for communication with a peer channel adapter via an InfiniBand™ link in an InfiniBand™ server system, according to a link width selected within the InfiniBand™ server system.
2. Background Art
Networking technology has encountered improvements in server architectures and design with a goal toward providing servers that are more robust and reliable in mission critical networking applications. In particular, the use of servers for responding to client requests has resulted in a necessity that servers have an extremely high reliability to ensure that the network remains operable. Hence, there has been a substantial concern about server reliability, availability, and serviceability.
In addition, processors used in servers have encountered substantial improvements, where the microprocessor speed and bandwidth have exceeded the capacity of the connected input/output (I/O) buses, limiting the server throughput to the bus capacity. Accordingly, different server standards have been proposed in an attempt to improve server performance in terms of addressing, processor clustering, and high-speed I/O.
These different proposed server standards led to the development of the InfiniBand™ Architecture Specification, (Release 1.0), adopted by the InfiniBand™ Trade Association. The InfiniBand™ Architecture Specification specifies a high-speed networking connection between end nodes (e.g., central processing units, peripherals, etc.) and switches inside a server system. Hence, the term “InfiniBand™ network” refers to a private system area network (SAN) that connects end nodes and switches into a cluster within a server system, enabling the sharing of cluster resources. The InfiniBand™ Architecture Specification specifies both I/O operations and interprocessor communications (IPC).
A particular feature of InfiniBand™ Architecture Specification is the proposed implementation in hardware of the transport layer services present in existing networking protocols, such as TCP/IP based protocols. The hardware-based implementation of transport layer services provides the advantage of reducing processing requirements of the central processing unit (i.e., “offloading” processor code execution), hence offloading the operating system of the server system.
However, arbitrary hardware implementations may result in substantially costly or relatively inefficient hardware designs. For example, the InfiniBand™ Architecture Specification specifies a number of different link bit rates. The lowest bit rate of 2.5 gigabits per second (Gb/s) is referred to as the 1× (“times 1”) link. Other link rates include 10 Gb/s (4×) and 30 Gb/s (12×). According to the InfiniBand™ Architecture Specification, during initialization of the network, link partners will determine their respective capabilities and send each other a link management packet specifying the link width to be used as the currently active link width.
However, no proposal has been made for an efficient manner for implementing a link layer module capable of efficiently supporting different link widths.